Bicycle power meter

ABSTRACT

A power meter for a bicycle includes a body having a torque input section and a torque output section, the body configured to transmit power between the torque input section and the torque output section. The power meter also includes a printed circuit board (“PCB”) having a substrate and at least one strain measurement device which may be attached to the PCB. The power meter may be integrally constructed with a chainring construction.

BACKGROUND OF THE INVENTION

A bicycle rider may desire information regarding the amount of powerbeing input, output, or removed from the drive train of a bicycle duringuse. Power meters may be configured to detect and/or measure this power,and/or output or otherwise provide this amount of power. Bicycle powermeters may use deformation or strain measurement devices, such as straingauges, to measure deflection and/or deformation of a bicycle componentduring use to establish the amount of power. Traditionally theinstallation, positioning, and/or placement of these strain measurementdevices is a difficult and tedious task as each strain measurementdevice would be individually positioned, placed, and/or coupled to thebicycle component, for example manually with a set of forceps ortweezers. After attaching to the component, the strain measurementdevices were then communicatively coupled in some way to processingcircuits installed separately and/or subsequently to the strainmeasurement devices. This traditional type of strain measurement deviceand separate circuitry construction and assembly requires a significantamount of effort, and is very costly.

SUMMARY

In an embodiment, a chainring structure includes a torque output sectioncomprising a plurality of sprockets having two axially boundingsprockets defining an inner-most and outer-most sprocket. The chainringstructure also includes a torque input section configured to attach to acrank assembly. The chainring structure also includes a power meterchamber disposed radially between the torque input section and thetorque output section, the power meter chamber including a base surfaceof a strain measurement section. A power meter is disposed in the powermeter chamber and has at least one strain measurement device attached tothe base surface. The torque output section, torque input section, andpower meter chamber of the chainring structure are formed as a unitarysingle piece and configured to dispose the base surface axially betweenthe axially bounding sprockets of the plurality of sprockets.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are side views of bicycles, which may be used to employ oneor more power meters;

FIGS. 2-4 illustrate an embodiment having a power meter integrated withcomponents of a bicycle drivetrain, such as the drivetrain for thebicycle of FIGS. 1A or 1B;

FIG. 5 is an exploded view of the power meter integrated with achainring carrier of FIGS. 2-4;

FIG. 6 is a perspective view of the chainring carrier of FIGS. 2-4;

FIGS. 7-9 illustrate various views of the chainring carrier of FIG. 6,with a cover removed;

FIGS. 10-12 illustrate various views of a printed circuit board (“PCB”)of the power meter of FIGS. 7-9;

FIGS. 13A-13D illustrate various views of a power meter integrated witha chainring;

FIGS. 14A-14B illustrate various views of a power meter integrated witha chainring;

FIG. 14C illustrates an exploded view of the power meter integrated withthe chainring of FIGS. 14A-14B;

FIG. 15A illustrates a perspective view of the power meter integratedwith multiple drive sprockets;

FIG. 15B illustrates the power meter integrated with multiple drivesprockets of FIG. 15A with the power meter cover removed to show theprinted circuit board assembly and power meter chamber;

FIGS. 15C-15E illustrate various view of the power meter integrated withmultiple drive sprockets of FIG. 15A;

FIG. 16A shows an expanded view of the cross section indicated in FIG.8;

FIG. 16B shows an expanded view of the area indicated in FIG. 16A;

FIG. 17 is a block diagram of an embodiment of a power meter system;

Other aspects and advantages of the embodiments disclosed herein willbecome apparent upon consideration of the following detaileddescription, wherein similar or identical structures have similar oridentical reference numerals.

DETAILED DESCRIPTION

Strain measurement devices may be physically integrated with theoperational circuitry of a bicycle power meter. Physically integratingstrain measurement devices and operational circuitry structure may causethe construction and/or precise positioning of power meter components tobe accomplished in a less expensive and/or less resource intensivemanner. The strain measurement devices may be attached directly to aphysical structure containing the power meter operational circuitry,such as a printed circuit board (“PCB”) substrate, thus coupling thestrain measurement devices and the power meter circuitry into a singularpower meter PCB assembly. Further, fixably attaching the strainmeasurement devices to the PCB such that the position of the strainmeasurement devices in a plane of the PCB substrate is fixed relative toother components of the PCB assembly may allow for easier alignmentand/or positioning of the strain measurement devices. For example, thealignment of the strain measurement devices may be established based onalignment of features of the PCB, which may be features of the PCBsubstrate and/or other PCB components.

Power meters may be used with different bicycle components to determinepower transmissions through the component. In an embodiment, the powermeter may be used in combination with the drive train of a bicycle. Forexample, the power meter may be integrated with a chainring and/or achainring carrier for measuring power transmitted from through the crankarms and/or shaft through the chainring drive assembly and to the chainor belt of the drivetrain. The power meter may also be integrated withother elements of the drivetrain, such as a rear cog or cassetteoperatively coupled with the rear wheel, a crank arm or pedal, and/or arear wheel hub.

Power meters may also be coupled with other components, such as one ormore brake rotors of a bicycle with a disc-braking system. The powermeter may be configured so as to dispose strain measurement devicesradially between a wheel hub attachment section and one or more frictionsurfaces of a rotor and/or rotor assembly. Strain measurement devicesdisposed in this manner can measure the strain of the rotor and/or rotorassembly caused by the dissipation of motive forces between rotationalforces of the road acting on the front and/or rear wheel of the bicycleand the friction surfaces of the rotor and/or rotor assembly where themotive forces are dissipated into other forms of energy, such as heatenergy. This is believed to provide a measure of braking power or powerdissipation of the braking system. In an embodiment, the power meter maybe integrated with a carrier of the rotor and/or rotor assembly. Assuch, one or more strain measurement devices may be disposed on thecarrier radially between a torque input section and a torque outputsection of the rotor carrier. For example, the one or more strainmeasurement devices may be disposed on the rotor carrier between aradially inner wheel hub connection section and a radially outerattachment section to an annular rotor member, the annular rotor membercontaining the friction or power dissipation surfaces.

In an embodiment, the power meter may be configured for use in anapplication wherein the transmission of power across a componentinvolves a dissipation of energy as heat energy, such as a brake rotorapplication. To accommodate the additional heat energy, and/or thedissipation thereof, the power meter may include heat dissipationfeatures, such as ribs, fins, or other features. For example, a rotorassembly may include a carrier, and the carrier may include the heatdissipation features. The heat dissipation features may be disposedand/or formed on a surface of the carrier, facilitating the transfer ofthe heat energy into an ambient environment, such as the surroundingair. These features dissipate the heat energy to maintain and/or limit atemperature of the rotor assembly to protect a PCB assembly of the powermeter.

A bicycle may use multiple power meters. In an embodiment, a bicycleincludes at least one power meter configured to measure the power inputto the drive train of the bicycle, and at least one power meterconfigured to measure the power dissipated by the braking system. Forexample, a first power meter may be integrated with at least onechainring of the drivetrain, as is described herein, and a second andthird power meter may be integrated with a front rotor and a rear rotorof the bicycle braking system, respectively. The values from these threepower meters may be used to compare the amount of power input to thebicycle, and the amount of power dissipated by the braking system. Thedifference between these values may be attributed to rolling resistanceof the bicycle, air resistance due to ambient air surrounding thebicycle during use, or other factors. In an embodiment, the three powermeters are configured to transmit the measure power values to one ormore component of the bicycle, such as a cycle computer, or otherportable computing device or computer. For example, the three powermeters may be configured to transmit the values representing themeasured power to a same bicycle component, mobile computing device, orcomputer.

FIGS. 1A-1B generally illustrate bicycles 100 with which a power metermay be used. The bicycle 100 includes a frame 38, front and rear wheels79, 78 rotatably attached to the frame 38, and a drivetrain 70. A frontbrake 92 is provided for braking the front wheel 79 and a rear brake 91is provided for braking the rear wheel 78. The front and/or forwardorientation of the bicycle 100 is indicated by the direction of arrow“A.” As such, a forward direction of movement for the bicycle isindicated by the direction of arrow A.

The illustrated bicycle 100 may be a road bike having drop-stylehandlebars 22, a mountain bike, or any other type of bicycle. Thepresent invention has applications to bicycles of any type, includingfully or partially suspensioned mountain bikes and others, as well asbicycles with mechanically controlled (e.g. cable, hydraulic, pneumatic)and non-mechanical controlled (e.g. wired, wireless) drive systems.

The bicycle 100 may include one or more shift units 26, mounted to thehandlebars 22. A front gear changer or front gear shift mechanism 30,such as a front derailleur, may be positioned on the frame 38, such ason the seat tube 32, adjacent the front sprocket assembly 34 so as toeffect gear changes to the front sprockets or an associated structure. Arear gear changer or rear gear shift mechanism 36, such as a rearderailleur, is mounted to a member of the frame 38 of the bicycle, suchas a mount, rear dropout, and/or an associated structure, in a positionto effect gear changes in a rear sprocket assembly 41. In someembodiments, the bicycle may only include a front or only a rear gearchanger.

The drivetrain 70 comprises a chain 72, the front sprocket assembly 34,which is coaxially mounted with a crank assembly 74, and the front gearchange mechanism 30, such as a derailleur. The drivetrain also includesthe rear sprocket assembly 41 coaxially mounted with the rear wheel 78,and the rear gear change mechanism 36, such as a rear derailleur.

The crank assembly 74 includes pedals 76, two crank arms 75, and a crankspindle (not shown) connecting the two crank arms 75. The crank assemblymay also include other components. For example, the crank assembly 74may also include a chainring carrier or spider 77 configured to transfertorque between one or more of the crank arms 75 and the front sprocketassembly 34. In another embodiment, the crank arms 75 and the frontsprocket assembly 34 may be torque transmittingly coupled in other ways,such as by being directly attached to the crank spindle.

The drivetrain 70 may also include a power meter 200. The power meter200 may be configured to be coupled with, or a part of, the crankassembly 74. The power meter 200 may be integrated with a body, such asthe chainring carrier 77 or rotor carrier 577, and may include one ormore strain measurement devices 260, such as strain gauges, arranged ina generally annular pattern about the body. The strain measurementdevices 260 are connected to circuitry and/or other sensors to generatepower information, which may be transmitted to another bicycle componentor external device for further processing and/or display. Alternatively,the power meter 200 may be coupled with the chainring assembly 34directly, for example without the use of a chainring carrier 77.

The power meter 200 may also, or alternatively, be included with othercomponents of the bicycle. In an embodiment, such as that shown in FIG.1B, the power meter 200 may be integrated with a braking system tomeasure and/or otherwise detect braking power. For example, the powermeter 200 may be integrated with one or more rotors 500 of adisc-braking system. As illustrated in FIG. 1B, a disc-braking systemmay be a system having a caliper 94 configured to apply a braking forceto the rotor 500. Including a power meter with a brake rotor 500 mayallow a user to determine the power dissipated by the braking system.Including a power meter with the brake rotor 500 may also, oralternatively, provide an indication of the braking forces applied tothe rotor 500.

As is illustrated in FIG. 1B, a bicycle 100 may include one or morepower meters. For example, the bicycle may have a power meter configuredto measure power input to the drive train 70 and the bicycle may haveone or more power meters configured to measure brake forces and/or powerdissipation. For example, the bicycle 100 may include a power meter 200integrated with brake rotors 500 configured in the braking systems ofthe front wheel 79 and the rear wheel 78. In an example, the bicycle 100may include a power meter 200 integrated with brake rotors 500configured in the braking systems of the front wheel 79 and the rearwheel 78.

The power meter 200 may include an annular printed circuit board (“PCB”)with strain measurement devices attached directly to the PCB. Forexample, the strain measurement device may be electrical resistance typestrain gauges that are generally planar and/or laminar in constructionwith a layer of conductive metal formed in one or more patterns on anon-electrical substrate, film, paper, or other material. The conductivemetal pattern or patterns may be formed of various metallicconstructions, including foil and/or wire. The conductive metal patternor patterns may be formed of any metal or metal alloy. For example,copper or copper alloys such as constantan may be used. Planar strainmeasurement devices also may include electrical contact connectionsurfaces configured for connection to circuitry of the PCB.

The PCB has a substrate to which components of the PCB are appliedand/or attached. The substrate may form the structure and/or shape ofthe PCB. The substrate may be any substance operable to form theunderlying attachment of the PCB components. For example, silicon,silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide(“GaAs”), an alloy of silicon and germanium, or indium phosphide(“InP”), may be used. The substrate may be rigid or flexible. In anembodiment, the substrate forms an annular rigid ring. The rigid ringmay be one continuous piece of substrate material. In an embodiment, asubstrate ring has an inner diameter and an outer diameter defining theextents of the substrate there between. In an embodiment, the substratemay be sized, shaped, and/or otherwise configured to position strainmeasurement devices relative to a body of a bicycle component so as tomeasure torsional strain, such as the strain caused by the relativedifference in rotation of an inner radial position of the body and anouter radial position of the body.

The connection to the circuitry of the PCB may be accomplished using anytechnique. In an embodiment, the connection is accomplished through anapplication of layer of a conductive medium, such as solder, between theelectrical contact connection surfaces of the planar strain measurementdevice and contact connection surfaces of the PCB which provideelectrically communicative contact with other electronic componentsconnected to the PCB, such as a processor, memory, other sensors, and/orother electric or electronic devices. Such connection may be madedirectly, without the use of an intermediate conductive connector, suchas an elongated electrical lead, wire, or other device. For example, theconductive medium may be bounded on opposing sides by the electricalcontact connection surfaces of the PCB and strain measurement device. Inthis example, the electrical contact connection surfaces of the PCB andstrain measurement device may be secured substantially parallel andopposing each other by the conductive medium. Further, as is describedabove, the connection may provide that the strain measurement device isfixably attached to the PCB substrate such that the strain measurementdevice is secure and not movable in a radial plane of the PCB substraterelative to other features and/or components of the PCB. As describedherein, the PCB may be attached to a body of a drivetrain to form apower meter. Such a body may be any body having a torque input sectionand torque output section. For example, drive train components such as achainring, a chainring carrier, a crank arm, a spindle, and/or a pedalmay be used as a body for attachment of the PCB, or components of thePCB. Alternatively, the PCB may stand alone as the power meter.

FIGS. 2-4 show a body, such as a chainring carrier and/or crank arm, ofa bicycle drivetrain having an integrated power meter 200. The bicycledrivetrain may be the drivetrain 70 for the bicycle 100 of FIGS. 1A or1B. FIG. 2 shows a perspective view of the drivetrain components, FIG. 3shows a top view of the drive train components, and FIG. 4 shows abottom view, opposing that of FIG. 3, of the bicycle components. In thisembodiment, the body is a chainring carrier 77, or spider. The chainringcarrier 77 may be made of any material operable to transmit torque, anda resulting power, between a torque input section (225 described belowwith respect to FIGS. 5-9) and a torque output section 222. For example,aluminum alloys may be used. A crank arm 75 is shown attached to thechainring carrier 77. The crank arm 75 has a pedal attachment section102 to which a pedal 76 may be attached such that a bicycle rider mayinput pedaling forces into the bicycle drive train. These pedalingforces result in a torque that causes the crank arm 75 and attachedchainring carrier to rotate about a crank or rotation axis 105. Thecrank arm 75 has a spindle attachment feature 108 that provides forattachment to a spindle that connects a crank arm and pedal assemblydisposed on an opposing side of the bicycle to facilitate pedaling withboth feet of the bicycle rider. The spindle attachment feature 108 maybe any feature operable to transfer torque, such as a splined interface.As such, torque from either crank arm 75 may be transferred into thechainring carrier 77 through the crank arm 75 attachment to thechainring carrier 77. The crank arm 75 may be attached to the chainringcarrier 77 using any technique operable to transmit torque between thecrank arm 75 and a torque input section 225 of the chainring carrier 77.In an embodiment, the crank arm 75 is connected as is described in U.S.Patent Application Publication 2015/0082939.

For example, a crank arm 75 and chainring carrier 77 may be attachedwith corresponding features and with a distinct torque transmittingconnection, such as with a bolted connection. In this example, thechainring carrier 77 is sized and shaped to connect to the crank arm 75.A first pairing feature 131 is formed on one of the crank arm 75 and thechainring carrier 77 and a second pairing feature 132 is formed on theother of the crank arm 75 and the chainring carrier 77 to position thechainring carrier on the crank arm. A clearance 133 is defined betweenthe first and second pairing features 131, 132 when the first and secondpairing features 131, 132 are paired. A torque-transmitting coupling130, such as through bolted connection, is formed on the crank arm 75and the chainring carrier 77 configured to transmit substantially all ofthe torque applied to the chainring carrier 77 from the crank arm 75.

A power meter cover 202 is provided to protect other power metercomponents installed within and/or on the body, such as a PCB assemblydescribed below with respect to FIGS. 9-12. The power meter cover 202may be constructed of any material operable to provide for theprotection of the internal power meter 200 components. For example,aluminum alloys may be used. In an embodiment, the power meter 200 maycommunicate signals wirelessly and the power meter cover 202 may be madeof a material that is radio frequency (“RF”) transparent, such aspolycarbonate or other materials. Also, a raised section 213 of a cover212, as is illustrated in the embodiment, may be configured so as tocover an antennae and/or other wireless communication device of thepower meter, and the raised section may be provided in an RF transparentmaterial. Further, the raised section 213 may be formed of an RFtransparent material and the rest of the cover may be formed of amaterial having a higher interference with RF signals, such as a metalor carbon fiber composite. The power meter cover 202 may be attached tothe body, in this embodiment the chainring carrier 77, using anytechnique. For example adhesives may be used to attach the power metercover 202. A power supply casing 204 is also provided to both secure andprotect a power supply for the power meter 200. In an embodiment, thepower supply casing 204 includes a removable power supply cover 205 toprovide access to the power supply. A torque output section 222 is shownon the chainring carrier 77. Provided in the torque output section 222in the displayed embodiment are torque output member attachment features224, such as a plurality of bolt holes, which are configured to provideattachment to a chainring or other torque transmitting component of thebicycle drivetrain.

The chainring carrier 77 includes a strain measurement section 230,which may include one or more strain measurement features 232. Thestrain measurement features 232 are formed into the chainring carrier 77to provide for positioning of strain measurement devices to detectand/or quantify mechanical deformations of the chainring carrier 77 dueto torque applied between the torque input section 225 and the torqueoutput section 222. For example, the strain measurement devices may beelectrical resistance type strain gauges attached to the strainmeasurement features 232.

FIGS. 5-9 show the chainring carrier 77 of FIGS. 2-4. FIG. 5 illustratesan exploded view of the chainring carrier 77 and other components of thepower meter 200. FIG. 6 shows a perspective view of the chainringcarrier 77. FIG. 7 shows a perspective view of the chainring carrier 77with the power meter cover 202 removed. FIG. 8 shows a top view of thechainring carrier 77 with the power meter cover 202 removed, and FIG. 9shows the same top view of the chainring carrier 77 with the powersupply components hidden from view. As used herein, a power meter mayinclude various components. In an embodiment, a power meter may includeall of the components indicated in FIG. 5. More or fewer components maybe included in the power meter 200. For example, the power meter may bethe components of FIG. 5, without the chainring carrier 77.

As shown in FIGS. 5 and 7-9 the chainring carrier 77 includes a cavity207 configured for installation of the PCB assembly 250 and/or otherpower meter 200 components. The cavity 207 may include an alignmentfeature 209 which corresponds to substrate alignment feature 254 formedin a substrate 252 of the PCB assembly 250. As can be seen in FIG. 9,wherein the power supply components are hidden from view, through thecorrelation of these alignment features 254, 209 the PCB assembly 250may be appropriately aligned with the chainring carrier 77. Otheralignment features may also be used and/or formed into the PCB substrate252.

The PCB assembly 250 also includes a plurality of strain measurementdevices 260 attached to the substrate 252 and/or other parts of the PCBassembly 250. The strain measurement devices 260 are configured toprovide a signal indicative of strain in an attached body. The signalmay be interpreted and acted upon by circuitry 28 of the power meter,for example as is described with respect to the power meter system 40 ofFIG. 17. The circuitry 28 may be configured to interpret the signalindicative of strain, and calculate a corresponding mechanical powerbeing transmitted through the attached body.

In the displayed embodiment the strain measurement devices 260 areattached at strain measurement device attachment features 258 formed inthe substrate 252. Further features and/or characteristics of the PCBassembly 250 are discussed below with respect to FIGS. 10-12.

In the displayed embodiment, the strain measurement device attachmentfeatures 258 form a vacancy or void. The void may provide access to thestrain measurement devices 260 in an axial direction of the PCB assembly250, such as along a direction of the axis of rotation 105. This accessmay be used during installation of the PCB assembly 250 into a body suchas the chainring carrier 77. For example, to generate a qualityattachment of the strain measurement devices 260 a clamp may be used forattachment to the body during a curing process. As shown, the strainmeasurement device attachment features 258 are configured to allow theattachment of the strain measurement devices 260 so that the strainmeasurement devices do not protrude beyond an inner diameter 251 of thesubstrate 252. This configuration may provide for a maximized substrate252 surface area available for circuitry implementation, but a minimizedtotal surface area of the PCB assembly, particularly in an annularsubstrate implementation wherein such a configuration may optimizeand/or minimize the radial extents of the PCB assembly installation.Further, the strain measurement device attachment features 258 may bedisposed so as to circumferentially correlate with bolt holes 224 of thetorque output section 222. For example, the device attachment features258 may be circumferentially separated by an angle Θ. In an embodiment,the angle Θ may be 10 degrees to 20 degrees. In an embodiment, a numberof strain measurement device attachment features matches a number ofstrain measurement features and/or bolt holes 224 of a torque outputsection 222.

As shown, the strain measurement devices 260 are attached at a radiallyinner edge of the substrate 252. Alternatively, the strain measurementdevices 260 may be attached at a radially out edge of the substrate 252,or between the radially inner and radially outer edge of the substrate252.

The power supply for the power meter 200 is attached both physically andelectrically using a contact structure 206 and a metallic screw 203. Asshown, the alignment feature 209 also provide for the attachment of thepower supply for the power meter 200 using the metallic screw 203.Alignment features may be provided without facilitation for power supplyattachment as well.

FIGS. 10-12 show the PCB assembly 250 of the power meter 200. FIG. 10shows a top perspective view of the PCB assembly 250. FIG. 11 shows atop view of the PCB assembly 250, and FIG. 12 shows a bottom perspectiveview of the PCB assembly 250. The PCB assembly 250 includes circuitry 28as is described further with respect to FIG. 17 below. The circuitry 28may involve one or more processors 20, as well as other electric and/orelectronic components as well as additional sensors 93, such as anaccelerometer. The circuitry may also include one or more antennae 290as part of the communication interface 90. Additional or alternativealignment features 255, 256 used for aligning the PCB assembly 250 to abody of a bicycle drivetrain may be formed into the substrate 252 of thePCB. For example, one or more notches 255 may be cut into an interiorand/or exterior edge of the substrate 252. The notches 255 may beconfigured to correspond to corollary features of the body to which thePCB assembly 250 is to be attached. Also, one or more holes 256 may beformed in the substrate 252 which may be used by an assembly tool orhandler to specifically attach to the PCB assembly 250 in a particularorientation. The tool and/or handler may then be aligned to the body towhich the PCB assembly is to be attached such that the PCB assembly 250is aligned properly to the body. For example, the alignment features256, 255, 254 may be used independently or in combination to align theone or more strain measurement devices 260 to the body.

The substrate 252 operates to connect, and/or provide structure for thecircuitry and attached components of the PCB assembly 250. The substrate252 may be flexible or rigid. In an embodiment, the substrate 252 is arigid substrate providing a durable basis for the PCB assembly 250. Thesubstrate 252 is formed to provide shape and other substance for the PCBassembly 250. For example, as shown, the substrate 252 is formed in anannular construction and/or shape. Such an annular shape facilitatesinstallation of the PCB assembly 250 around a torque input section of abody.

At least one strain measurement device 260 may be attached to the PCBassembly 250 such that the at least one strain measurement device 260 isfixed in a plane P of the PCB assembly 250 relative to at least onefeature of the PCB assembly 250. For example, the strain measurementdevices 260 may be fixed relative to one or more of the alignmentfeatures 254, 255, 256 and/or a circuitry 28 component such as theprocessor 20. The plane P may be a plane formed to include the substrate252. In an embodiment, the plane P is perpendicular to the axis ofrotation 105. An annular construction of the substrate 252, and rigidattachment of the strain measurement devices 260 as described above,provides for the disposition of a plurality of strain measurementdevices 260 around the annular shape and about the torque input section.Such an annular construction also allows for the disposition of thestrain measurement devices between the torque input section and thetorque output section.

In an embodiment, a chainring structure may be formed with an integratedpower meter chamber that is configured to house a power meter 200. Thepower meter chamber includes a base surface that is configured forattachment to the power meter 200. For example, the base surface may beconfigured for attachment to strain gauges of the power meter 200. Thechainring structure includes teeth in the power output section. Forexample, the chainring structure may include teeth forming one or moresprockets. The particular disposition of the base surface relative tothe teeth and/or sprockets can affect an accuracy of a measurement oftorque and/or power transmitted through the chainring structure. In anembodiment, the particular relative disposition of the base surfacerelative to the sprockets and teeth along a rotational axis of thechainring structure can affect the measurement of the torque and/orpower transmitted through the chainring structure using the power meter200.

FIGS. 13A-13D show an embodiment having a power meter 200 integratedwith a chainring structure 300A. FIG. 13C shows a cross sectional viewof the power meter 200 integrated with the chainring structure 300A asis indicated in FIG. 13B. FIG. 13D shows an enlarged view of a portionof the power meter 200 integrated with the chainring structure 300A asindicated in FIG. 13C. The chainring structure 300A also includes apower meter cover 202A and/or a power supply cover 204A.

In the embodiment illustrated in FIGS. 13A-13D, the chainring structure300A includes a first type of tooth 323C and a second type of tooth323D. The second type of tooth 323D is configured to interactspecifically with an outer link space and plates of a roller drive chainfor a bicycle. The first type of tooth 323C is configured to interactspecifically with an inner link space and plates of a roller drive chainfor a bicycle. In an embodiment, as is illustrated in FIGS. 13A-13D, thesecond type of tooth 323D is axially wider than the first type of tooth323C. For example, the second type of tooth 323D may include axialprotrusions 324A, 324B configured to fill the outer link space and/orinteract with outer link plates of a roller drive chain for a bicycle.There may be an inboard protrusion 324A and/or an outboard protrusion324B on the second type of tooth 323D. In an embodiment, the first typeof tooth 232C is free of protrusions on the outboard and inboard sides,while the second type of tooth includes protrusions on the outboard 324Band/or inboard side 324A. The outboard protrusion 324B and the inboardprotrusion 324A may provide the same or different axial widths from atooth centerline.

In an embodiment, as is illustrated in FIGS. 13A-13D, the chainringstructure 300A includes a torque output section 322 comprising aplurality of teeth 323C, 323D configured as a sprocket 501, for example,a power output sprocket for the chainring structure 300A. The powermeter 200 is integrated with the chainring structure 300A and disposedin a power meter chamber 506 formed in the chainring structure 300A. Thechainring structure 300A also includes a torque input section 325configured to attach to a crank assembly of a bicycle.

The chainring structure 300A includes the power meter chamber 506disposed radially between the torque input section 325 and the torqueoutput section 322, the power meter chamber 506 includes a base surface508 of a strain measurement section 230. The power meter 200 has atleast one strain measurement device attached to the base surface 508.

In the embodiment illustrated in FIGS. 13A-13D, the torque outputsection 322, torque input section 325, and power meter chamber 506 ofthe chainring structure 300A are formed as a unitary single piece andconfigured to dispose the base surface 508 axially outboard of thesprocket 501. For example, the base surface 508 may be disposed outboardof a center T of the plurality of one or both of the two different typesof teeth 323C, 323D. In an embodiment, the base surface 508 may bedisposed outboard of the outboard protrusion 324B of the second type ofteeth 323D.

In this embodiment, the chainring structure 300A includes a PCB assemblyinstallation section 305. The chainring structure also includes a torqueinput section 325, configured similarly to the torque input section 225described above with regard to the chainring carrier 77. The chainringstructure 300A also includes a torque output section 322 that includes aplurality of teeth 323C, 323D, as described above, configured tooperationally interact with, and transmit torque to, a bicycle chain,such as the bicycle chain 72 described with respect to FIGS. 1A and 1B.The displayed embodiment also includes a PCB assembly 250, a power metercover 202A and/or power supply cover 204A of the power meter 200.

FIGS. 14A and 14B show another embodiment having a power meter 200integrated with a chainring structure 300B. FIG. 14C illustrates anexploded view of the chainring structure 300B, FIG. 14A shows aperspective view of the chainring structure 300B with the power metercover 202 removed, and FIG. 14B shows a top view of the chainring 300Bwith the cover 202 removed.

In this embodiment, the chainring structure 300B includes a PCB assemblyinstallation section 305. The chainring structure also includes a torqueinput section 325, configured similarly to the torque input section 225described above with regard to the chainring carrier 77. The chainringstructure 300B also includes a torque output section 322 that includes aplurality of teeth 323 configured to operationally interact with, andtransmit torque to, a bicycle chain, such as the bicycle chain 72described with respect to FIGS. 1A and 1B. The displayed embodiment alsoincludes a PCB assembly 250, a power meter cover 202, and power supplycomponents 204, 205 of the power meter 200.

FIGS. 15A-15E shows an embodiment similar to the embodiment shown inFIGS. 13A-13D and 14A-14C, but the torque output section 322 includestwo pluralities of teeth 323A and 323B disposed as different drivesprockets for the drivetrain. The two pluralities of teeth 323A and 323Bare formed as a small sprocket 502 and a large sprocket 504, the smallsprocket having a smaller effective diameter and/or fewer teeth than thelarge sprocket.

In this embodiment, the chainring structure 300C includes a torqueoutput section 322 comprising a plurality of sprockets having twoaxially bounding sprockets 502, 504 defining an inner-most 502 andouter-most sprocket 504. The power meter 200 is integrated with thechainring structure 300C and disposed in a power meter chamber 506. Thechainring structure 300C also includes a torque input section 325configured to attach to a crank assembly.

The chainring structure 300C includes a power meter chamber 506 disposedradially between the torque input 325 section and the torque outputsection 322, the power meter chamber 506 including a base surface 508 ofa strain measurement section 230. A power meter 200 is disposed in thepower meter chamber 506. The power meter 200 has at least one strainmeasurement device attached to the base surface 508. The torque outputsection 322, torque input section 325, and power meter chamber 506 ofthe chainring structure 300C are formed as a unitary single piece andconfigured to dispose the base surface 508 axially between the axiallybounding sprockets 502, 504 of the plurality of sprockets. The basesurface 508 may be disposed between centers A1, A2 of the sprocketsand/or the two pluralities of teeth 323A, 323B. In an embodiment, thebase surface 508 may be axially disposed in a space bounded by aninboard surface 524 of teeth 323A of a larger sprocket 504 and anoutboard surface 522 of teeth 323B of a smaller sprocket 502.

In an embodiment, the power meter chamber 506 is formed so as to disposea plane M that includes the base surface 508, at an angle a to an axisof rotation R of the plurality of sprockets. For example, as is shown inFIG. 15E, the power meter chamber 506 is formed as a unitary singlepiece so as to dispose a plane M perpendicular to an axis of rotation Rof the plurality of sprockets. The plane M includes the base surface 508and is between the bounding sprockets 502, 504.

As is illustrated in the embodiment illustrated in FIG. 15E, the torqueoutput section 322, torque input section 325, and power meter chamber506 are formed from a same material. For example, the torque outputsection 322, torque input section 325, and power meter chamber 506 maybe formed from aluminum or an aluminum alloy. Other materials such assteal may also be used.

In an embodiment the torque output section 322, torque input section325, and/or power meter chamber 506 are formed through a removal ofmaterial from a single piece of a same or common material. For example,the torque output section 322, torque input section 325, and power meterchamber 506 may be formed through a machining and/or milling process. Inan embodiment, the base surface 508 is formed through the removal ofmaterial from the single piece to expose the base surface 508. In anembodiment, there is a transition section 516 also formed between andconnecting the first sprocket 502 and the second sprocket 504. Thetransition section may be formed of the same single piece material asthe the first sprocket 502 and the second sprocket 504. In anembodiment, the teeth of the first sprocket 502 and/or the secondsprocket 504 are also formed of the same single piece material, forexample through material removal techniques such as machining ormilling. Other techniques may also be used to form the single piecematerial into the chainring structure. For example, stamping, forgingand/or other forming techniques may be used. Similarly, in an embodimentthe single sprocket chainring structure 300A, as illustrated in theembodiments shown in FIGS. 13A-13D and 14A-14C, may also be formed as asingle piece unitary structure, for example from a single piece ofmaterial through material removal or other processes.

In an embodiment the strain measurement section 230 includes at leastone strain measurement feature formed in the one piece unitary structureof the chainring structure 300C. The at least one strain measurementfeature may include the base surface 508. At least one strainmeasurement device may be attached to the strain measurement feature atthe base surface 508. The strain measurement device may be attached tothe base surface 508 using an adhesive, for example as is describedherein.

In an embodiment, the power meter comprises a printed circuit board(“PCB”) having a substrate 252, and the substrate 252 is of annularconstruction and disposed in the power meter chamber 506 around thetorque input section 325 of the chainring structure 300C. The at leastone strain measurement device may be a plurality of strain measurementdevices disposed about the torque input section 325 of the chainringstructure 300C.

FIGS. 16A and 16B illustrate close up views of the attachment of thestrain measurement devices 260 to the substrate 252 of the PCB and thebody 401. A volume of electrically conductive bonding material 405, forexample a fusible metal alloy such as tin, lead, brass, or silver basedsolder, is disposed between planar electrical contact surfaces 420 ofthe strain measurement device 260 and electrical circuitry contacts 422that are communicatively coupled to circuitry 28 of the PCB assembly.The volume of electrically conductive bonding material 405 involves atleast one distinct volume of electrically conductive bonding material,and the electrical circuitry contacts 422, and/or the substrate 252, andthe at least one strain measurement device 260 are in physical contactwith the distinct volume of electrically conductive bonding material405. The electrical circuitry contacts 422 may be embedded in thesubstrate 252.

The strain measurement device 260 may be laminar, and formed of multiplelayers. A base layer 432 may be formed to provide an attachment surfaceto be attached to the body 401 and a base insulative layer forconductive material 427 of the strain measurement patterns and/or theelectrical contact surfaces 420 of the strain measurement device 260. Acover layer 429 may be included to cover the conductive material 427layer. The cover layer 429 may not exist in an area of the electricalcontact surfaces 420 so as to leave the contact surfaces available forelectrical connection. The strain measurement patterns are disposed in asection 441 to be attached to the body 401. In the displayed embodiment,the section 441 is to be disposed generally flat and parallel to thecorrelating surface of the body 401.

The strain measurement device 260 is attached to the body 401 with anattachment material 425 that is appropriately rigid to transmit thedeformation of the body in a measurable way to the strain measurementdevice 260, but also resilient enough to avoid cracking or otherwisebreaking down due to repetitive deformation of the body. In anembodiment an adhesive, such as a cyanoacrylate based adhesive, is used.Polyester, Phenol, and/or epoxy based adhesives may also be used.

The PCB assembly and/or the substrate may be attached to the body usingany technique. In the displayed embodiment, a material 417 such as adouble sided adhesive tape, for example a foam adhesive tape, may beused to secure the PCB assembly to the body 401. Such attachment mayprovide for thermal and mechanical deformations of the body 401 to beisolated from the PCB assembly. Such attachment mechanisms, however, maycause the substrate 252 to which the strain measurement device 260 isattached, to have a significant void to be filled between the strainmeasurement device 260 and the body 401. This void may be filled withthe strain measurement device attachment material 425, however, theconfiguration may apply stresses to the strain measurement device 260that can cause buckling or other breakages of the conductive materiallayer of the strain measurement device 260.

To help alleviate this configuration issue, the strain measurementdevice 260 may also be attached to the substrate 252 of the PCB assemblywith a structural support material 415. The structural support material415 is configured to provide structural rigidity to the strainmeasurement device 260 as the device is deformed to form a connectionwith the body 401. A structural support fillet or other structure may beformed by the structural support material 415. The structural supportmaterial 415 may be disposed so as to be connected to the substrate 252and the cover layer 429 of the strain measurement device 260. In anembodiment, the structural support material 415 maintains an edge of thesubstrate and at least a portion of the strain measurement device 260 ina generally orthogonal or perpendicular orientation. The structuralsupport material 415 may be any material operable to provide therequisite rigidity. For example, an ultra-violet light curable adhesivemay be used.

FIG. 17 is a block diagram of an exemplary power meter system 40 for abicycle. The system 40 may be used alone to communicate with and/orcontrol bicycle components or other devices. The system 40 includescircuitry 28 which includes at least one processor 20 and a memory 10.In the illustrated embodiment, the circuitry 28 also includes a userinterface 82, a strain detection device interface 80, and acommunication interface 90. Circuitry 28 may also include componentconnections and/or electrically connecting materials embedded in asubstrate material. The system also includes at least one straindetection device 260 in communication with the strain detection devicecommunication interface 80. Additional, different, or fewer componentsare possible for the power meter system 40. For example, the userinterface 82 may not be included in a circuitry 28 and/or the powermeter system. Also, components may be combined. In an embodiment, thepower meter system is integrated with a component of a power train of abicycle, such as a chainring or chainring carrier, for example as isdescribed with respect to FIGS. 2-16.

The processor 20 may include a general processor, digital signalprocessor, an application specific integrated circuit (ASIC), fieldprogrammable gate array (FPGA), analog circuit, digital circuit,combinations thereof, or other now known or later developed processor.The processor 20 may be a single device or combinations of devices, suchas through shared or parallel processing.

The circuitry 28 is operable to interpret a signal indicative of strainfrom deformation of an attached body from one or more of the straindetection devices 260 and determine a corresponding power transmittedbetween the torque input and the torque output section. For example, thesignal may be communicated from the strain detection devices 260 to theprocessor 20 which may apply a conversion technique of the strain to apower transmitted across the body for a time period. Such a conversiontechnique may involve using the known material characteristics of thebody, such as the modulus of elasticity and a known geometry of thebody. Force values to cause amounts of strain measurable by the straindetection devices 260 may be known from these, or other, characteristicsof the power meter system. For example, these values, or indications ofthese values, may be stored on a memory 10. The measured strain valuesmay be matched against these values by the processor 20 to determine aninput force, and a resulting power over time transmitted by the body ofthe drive train.

The memory 10 may be a volatile memory or a non-volatile memory. Thememory 10 may include one or more of a read only memory (ROM), randomaccess memory (RAM), a flash memory, an electronic erasable program readonly memory (EEPROM), or other type of memory. The memory 10 may beremovable from the power meter system 40, such as a secure digital (SD)memory card. In a particular non-limiting, exemplary embodiment, acomputer-readable medium can include a solid-state memory such as amemory card or other package that houses one or more non-volatileread-only memories. Further, the computer-readable medium can be arandom access memory or other volatile re-writable memory. Additionally,the computer-readable medium can include a magneto-optical or opticalmedium, such as a disk or tapes or other storage device. Accordingly,the disclosure is considered to include any one or more of acomputer-readable medium and other equivalents and successor media, inwhich data or instructions may be stored.

The memory 10 is a non-transitory computer-readable medium and isdescribed to be a single medium. However, the term “computer-readablemedium” includes a single medium or multiple media, such as acentralized or distributed memory structure, and/or associated cachesthat are operable to store one or more sets of instructions and otherdata. The term “computer-readable medium” shall also include any mediumthat is capable of storing, encoding or carrying a set of instructionsfor execution by a processor or that cause a computer system to performany one or more of the methods or operations disclosed herein.

In an alternative embodiment, dedicated hardware implementations, suchas application specific integrated circuits, programmable logic arraysand other hardware devices, can be constructed to implement one or moreof the methods described herein. Applications that may include theapparatus and systems of various embodiments can broadly include avariety of electronic and computer systems. One or more embodimentsdescribed herein may implement functions using two or more specificinterconnected hardware modules or devices with related control and datasignals that can be communicated between and through the modules, or asportions of an application-specific integrated circuit. Accordingly, thepresent system encompasses software, firmware, and hardwareimplementations.

The power supply 84 is a portable power supply. The power supply mayinvolve the generation of electric power, for example using a mechanicalpower generator, a fuel cell device, photo-voltaic cells, or other powergenerating devices. The power supply may include a battery such as adevice consisting of two or more electrochemical cells that convertstored chemical energy into electrical energy. The power supply 84 mayinclude a combination of multiple batteries or other power providingdevices. Specially fitted or configured battery types, or standardbattery types such as CR 2012, CR 2016, and/or CR 2032 may be used.

The communication interface 90 provides for data and/or signalcommunication from the power meter system 40 to another component of thebicycle, or an external device such as a mobile phone or other computingdevice. The communication interface 90 communicates the data using anyoperable connection. An operable connection may be one in which signals,physical communications, and/or logical communications may be sentand/or received. An operable connection may include a physicalinterface, an electrical interface, and/or a data interface. Thecommunication interface 90 may be configured to communicate wirelessly,and as such include one or more antennae. The communication interface 90provides for wireless communications in any now known or later developedformat. Although the present specification describes components andfunctions that may be implemented in particular embodiments withreference to particular standards and protocols, the invention is notlimited to such standards and protocols. For example, standards forInternet and other packet switched network transmission (e.g., TCP/IP,UDP/IP, HTML, HTTP, HTTPS) represent examples of the state of the art.Such standards are periodically superseded by faster or more efficientequivalents having essentially the same functions. Bluetooth® and orANT+™ standards may also, or alternatively, be used. Accordingly,replacement standards and protocols having the same or similar functionsas those disclosed herein are considered equivalents thereof. In anembodiment, the communication interface 90 may be configured to transmita signal indicative of a power determined from a measured strain of abody. Further, the determined power may be transmitted wirelessly.

The strain detection device interface 80 provides for data and/or signalcommunication from one or more strain detection devices 260 to the powermeter circuitry 28. The interface 80 communicates using wired and/orwireless communication techniques. For example, the interface 80communicates with the strain detection devices 260 using a system bus,or other communication technique. The strain detection device interface80 may include additional electric and/or electronic components, such asan additional processor and/or memory for detecting, communicating,and/or otherwise processing signals of the strain detection devices 260.

The user interface 82 may be one or more buttons, keypad, keyboard,mouse, stylus pen, trackball, rocker switch, touch pad, voicerecognition circuit, or other device or component for communicating databetween a user and the power meter system 40. The user interface 82 maybe a touch screen, which may be capacitive or resistive. The userinterface 82 may include a liquid crystal display (“LCD”) panel, lightemitting diode (“LED”), LED screen, thin film transistor screen, oranother type of display. The user interface 82 may also include audiocapabilities, or speakers.

In an embodiment, the user interface 82 includes an LED indicator. TheLED indicator lights to indicate input of the commands or other actionsof the power meter system.

The communication interface 90 is configured to send and/or receive datasuch as control signals and/or commands to and/or from bicyclecomponents such as the front gear changer 30 and/or the shift units 26.The component communication interface 90 communicates the data using anyoperable connection. An operable connection may be one in which signals,physical communications, and/or logical communications may be sentand/or received. An operable connection may include a physicalinterface, an electrical interface, and/or a data interface. Thecommunication interface 90 provides for wireless communications in anynow known or later developed format. Although the present specificationdescribes components and functions that may be implemented in particularembodiments with reference to particular standards and protocols, theinvention is not limited to such standards and protocols. For example,standards for Internet and other packet switched network transmission(e.g., TCP/IP, UDP/IP, HTML, HTTP, HTTPS) represent examples of thestate of the art. Such standards are periodically superseded by fasteror more efficient equivalents having essentially the same functions.Accordingly, replacement standards and protocols having the same orsimilar functions as those disclosed herein are considered equivalentsthereof.

In accordance with various embodiments of the present disclosure,methods described herein may be implemented with software programsexecutable by a computer system, such as the circuitry 28. Further, inan exemplary, non-limited embodiment, implementations can includedistributed processing, component/object distributed processing, andparallel processing. Alternatively, virtual computer system processingcan be constructed to implement one or more of the methods orfunctionality as described herein.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a standalone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

As used in this application, the term ‘circuitry’ or ‘circuit’ refers toall of the following: (a) hardware-only circuit implementations (such asimplementations in only analog and/or digital circuitry) and (b) tocombinations of circuits and software (and/or firmware), such as (asapplicable): (i) to a combination of processor(s) or (ii) to portions ofprocessor(s)/software (including digital signal processor(s)), software,and memory(ies) that work together to cause an apparatus, such as amobile phone or server, to perform various functions) and (c) tocircuits, such as a microprocessor(s) or a portion of amicroprocessor(s), that require software or firmware for operation, evenif the software or firmware is not physically present.

This definition of ‘circuitry’ applies to all uses of this term in thisapplication, including in any claims. As a further example, as used inthis application, the term “circuitry” would also cover animplementation of merely a processor (or multiple processors) or portionof a processor and its (or their) accompanying software and/or firmware,as well as other electronic components. The term “circuitry” would alsocover, for example and if applicable to the particular claim element, abaseband integrated circuit or applications processor integrated circuitfor a mobile computing device or a similar integrated circuit in server,a cellular network device, or other network device.

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor receives instructions and data from a read only memory or arandom access memory or both. The essential elements of a computer are aprocessor for performing instructions and one or more memory devices forstoring instructions and data. Generally, a computer also includes, orbe operatively coupled to receive data from or transfer data to, orboth, one or more mass storage devices for storing data, e.g., magnetic,magneto optical disks, or optical disks. However, a computer need nothave such devices. Moreover, a computer can be embedded in anotherdevice, e.g., a mobile telephone, a personal digital assistant (PDA), amobile audio player, a Global Positioning System (GPS) receiver, or apower meter system 40 to name just a few. Computer readable mediasuitable for storing computer program instructions and data include allforms of non-volatile memory, media and memory devices, including by wayof example semiconductor memory devices, e.g., EPROM, EEPROM, and flashmemory devices; magnetic disks, e.g., internal hard disks or removabledisks; magneto optical disks; and CD ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,special purpose logic circuitry.

In an embodiment, a power meter for a bicycle includes a body comprisinga torque input section and a torque output section, the body configuredto transmit power between the torque input section and the torque outputsection. The power meter also includes a printed circuit board (“PCB”).The PCB includes a substrate, at least one strain measurement deviceattached to the substrate, the at least one strain measurement deviceconfigured to provide a signal indicative of strain detected in thebody, and circuitry, embedded in the substrate, the circuitry configuredfor interpreting the signal and determining a corresponding powertransmitted between the torque input and the torque output section. Inan embodiment, the at least one strain measurement device may beattached to the substrate such that the at least one strain measurementdevice is fixed in a plane of the PCB relative to at least one featureof the PCB. In an embodiment, the feature is formed in the substrate. Inan embodiment, the at least one strain measurement device may be a foilor wire type electrical strain gauge. In an embodiment, the torqueoutput section may include teeth. In an embodiment, the torque outputsection may include chainring attachment features. In an embodiment, theat least one strain measurement device may include planar electricalcontact surfaces, and the PCB may be configured such that the strainmeasurement device planar electrical contact surfaces are disposedfacing electrical circuitry contacts of the PCB, the electricalcircuitry contacts of the PCB communicatively coupled to both the strainmeasurement device planar electrical contact surfaces and the circuitryof the PCB. In an embodiment, the at least one strain measurement devicemay be communicatively coupled to the circuitry of the PCB with a volumeof an electrically conductive bonding material. In an embodiment, theelectrically conductive bonding material may be a fusible metal alloy.In an embodiment, the volume of electrically conductive bonding materialmay include at least one distinct volume of electrically conductivebonding material, and both the PCB and the at least one strainmeasurement device are in physical contact with the distinct volume ofelectrically conductive bonding material. In an embodiment, the at leastone strain measurement device may be attached to the body with anadhesive. In an embodiment, the at least one strain measurement deviceattachment to the PCB may include a structural support material. In anembodiment, the structural support material may be disposed both on anedge of the substrate and on a surface of the at least one strainmeasurement device. In an embodiment, the edge and the surface areoriented substantially orthogonal to each other. In an embodiment, thesubstrate may be of annular construction and disposed in the body aroundthe torque input section. In an embodiment, the at least one strainmeasurement device may include a plurality of strain measurement devicesdisposed about the torque input section. In an embodiment, the pluralityof strain measurement devices may be disposed so as to align with strainmeasurement features of the body. In an embodiment, the substrateincludes at least one strain measurement device attachment feature, andthe at least one strain measurement device may be disposed on thesubstrate so as to be aligned with the at least one strain measurementdevice attachment feature. In an embodiment, the strain measurementdevice attachment feature may include at least one vacancy formed in thesubstrate. In an embodiment, the vacancies are configured to provideaccess to the at least one strain measurement device in an axialdirection of the PCB. In an embodiment, the body further may includebolt holes in the torque output section configured for attachment to achainring, and the strain measurement device attachment features aredisposed so as to correlate to the bolt holes. In an embodiment, thepower meter may include a same number of strain measurement features andbolt holes. In an embodiment, the circuitry may be further configured towirelessly transmit a second signal indicative of the determined power.

In an embodiment a brake rotor includes a rotor carrier having a torqueinput section, and a torque output section. The brake rotor alsoincludes a printed circuit board (“PCB”) that includes a substrate, atleast one strain measurement device, the at least one strain measurementdevice configured to provide a signal indicative of strain detected inthe rotor carrier, and circuitry, attached to the substrate, thecircuitry configured for interpreting the signal and determining acorresponding power transmitted between the torque input and the torqueoutput section. The brake rotor also includes an annular rotor structureattached to the torque output section of the rotor carrier and having atleast one friction surface configured for generating friction todissipate power provided at the torque input section of the carrier. Thecarrier may also include heat dissipation features.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those of skill in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope of the disclosure.Additionally, the illustrations are merely representational and may notbe drawn to scale. Certain proportions within the illustrations may beexaggerated, while other proportions may be minimized. Accordingly, thedisclosure and the figures are to be regarded as illustrative ratherthan restrictive.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis specification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable sub-combination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a sub-combination or variation of a sub-combination.

Similarly, while operations and/or acts are depicted in the drawings anddescribed herein in a particular order, this should not be understood asrequiring that such operations be performed in the particular ordershown or in sequential order, or that all illustrated operations beperformed, to achieve desirable results. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the embodiments describedabove should not be understood as requiring such separation in allembodiments, and it should be understood that any described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.

One or more embodiments of the disclosure may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to voluntarily limit the scope of thisapplication to any particular invention or inventive concept. Moreover,although specific embodiments have been illustrated and describedherein, it should be appreciated that any subsequent arrangementdesigned to achieve the same or similar purpose may be substituted forthe specific embodiments shown. This disclosure is intended to cover anyand all subsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, are apparent to those of skill in the artupon reviewing the description.

The Abstract of the Disclosure is provided to comply with 37 C.F.R.§1.72(b) and is submitted with the understanding that it will not beused to interpret or limit the scope or meaning of the claims. Inaddition, in the foregoing Detailed Description, various features may begrouped together or described in a single embodiment for the purpose ofstreamlining the disclosure. This disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may be directed toless than all of the features of any of the disclosed embodiments. Thus,the following claims are incorporated into the Detailed Description,with each claim standing on its own as defining separately claimedsubject matter.

It is intended that the foregoing detailed description be regarded asillustrative rather than limiting and that it is understood that thefollowing claims including all equivalents are intended to define thescope of the invention. The claims should not be read as limited to thedescribed order or elements unless stated to that effect. Therefore, allembodiments that come within the scope and spirit of the followingclaims and equivalents thereto are claimed as the invention.

What is claimed is:
 1. A chainring structure, comprising: a torqueoutput section comprising a plurality of sprockets having two axiallybounding sprockets defining an inner-most and outer-most sprocket; atorque input section configured to attach to a crank assembly; a powermeter chamber disposed radially between the torque input section and thetorque output section, the power meter chamber including a base surfaceof a strain measurement section; a power meter disposed in the powermeter chamber and having at least one strain measurement device attachedto the base surface; the torque output section, torque input section,and power meter chamber formed as a unitary single piece and configuredto dispose the base surface axially between the axially boundingsprockets of the plurality of sprockets.
 2. The chainring structure ofclaim 1, wherein the power meter chamber is formed as a unitary singlepiece so as to dispose a plane perpendicular to an axis of rotation ofthe plurality of sprockets and including the base surface between thebounding sprockets.
 3. The chainring structure of claim 1, wherein thetorque output section, torque input section, and power meter chamber areformed from a same material.
 4. The chainring structure of claim 3,wherein the same material is aluminum or an aluminum alloy.
 5. Thechainring structure of claim 3, wherein the torque output section,torque input section, and power meter chamber are formed through aremoval of material from a single piece of the same material.
 6. Thechainring structure of claim 5, wherein the base surface is formedthrough the removal of the same material from the single piece to exposethe base surface.
 7. The chainring structure of claim 1, wherein thestrain measurement section comprises at least one strain measurementfeature.
 8. The chainring structure of claim 1, wherein the at least onestrain measurement device comprises planar electrical contact surfaces,and the power meter comprises a printed circuit board (“PCB”), the PCBbeing configured such that strain measurement device planar electricalcontact surfaces are disposed facing electrical circuitry contacts ofthe PCB, the electrical circuitry contacts of the PCB communicativelycoupled to both the strain measurement device planar electrical contactsurfaces and the circuitry of the PCB.
 9. The chainring structure ofclaim 8, wherein the at least one strain measurement device attachmentto the PCB comprises a structural support material.
 10. The chainringstructure of claim 1, wherein the at least one strain measurement deviceis a foil or wire type electrical strain gauge.
 11. The chainringstructure of claim 1, wherein the at least one strain measurement deviceis communicatively coupled to the circuitry of a printed circuit board(“PCB”) of the power meter with a volume of an electrically conductivebonding material.
 12. The chainring structure of claim 11, wherein theelectrically conductive bonding material is a fusible metal alloy. 13.The chainring structure of claim 11, wherein the volume of electricallyconductive bonding material comprises at least one distinct volume ofelectrically conductive bonding material, and both the PCB and the atleast one strain measurement device are in physical contact with thedistinct volume of electrically conductive bonding material.
 14. Thechainring structure of claim 1, wherein the at least one strainmeasurement device is attached to the base surface with an adhesive. 15.The chainring structure of claim 1, wherein the power meter comprises aprinted circuit board (“PCB”) having a substrate, and the substrate isof annular construction and disposed in the power meter chamber aroundthe torque input section.
 16. The chainring structure of claim 15,wherein the at least one strain measurement device comprises a pluralityof strain measurement devices disposed about the torque input section.17. The chainring structure of claim 15, wherein the at least one strainmeasurement device is attached to the substrate.